D. Van Nostrand Company, 1961
Buku Teks
MacDonald, Theodore H.
Hale & Iremonger, 1989
Buku Teks
Azumah, John Alembillah, author
Oneworld , 2001
Buku Teks
[publisher not identified], 1999
Buku Teks
Murdock, George Peter, author
McGraw-Hill, 1959
Buku Teks